In the drilling and production of oil and gas wells, it is often necessary to obtain inner surface information concerning conditions present within the borehole. For example, tools and other objects may become lodged in the borehole during the drilling of a well. Such objects must be retrieved before drilling can continue.
In the operation and/or periodic maintenance of producing or injection wells, it is frequently necessary to obtain information about the construction and/or operating condition of production equipment located downhole. For example, detection of the onset of corrosion damage to well tubing or casing within a borehole enables the application of anti-corrosive treatments to the well. Early treatment of corrosive well conditions prevents the highly expensive and dangerous replacement of corrosion damaged well production components.
For performing other maintenance operations in a production well environment, such as replacement of various flow control valves or the inspection of the location and condition of casing perforations, it is highly desirable for an operator located at the surface to obtain accurate, real-time information about downhole conditions.
In fact, new regulations require operators of oilfields to perform a visual inspection of their safety/barrier valves after certain operations to verify cleanness in order to secure a further safe operation. These are often referred to as BlowOut Preventers (BOP) which are large, specialized valves or similar mechanical devices, usually installed redundantly in stacks, used to seal, control and monitor oil and gas wells, and intended to prevent tubing (e.g. drill pipe and well casing), tools and drilling fluid from being blown out of the wellbore (also known as borehole, the hole leading to the reservoir) when a blowout threatens.
Other tubulars may need inspection. This is the case of risers, large tubulars connecting Oil and Gas exploration or production platforms or ships to subsea installations.
Visual inspection involves inserting an apparatus with sensors into the pipe and lowering it towards the oil and/or gas reservoir. The apparatus is a camera tool adjusted for visual inspection. The sensors build into the tool apparatus may also measure temperature, pressure or other variables of interest. In combination with the depth may these values be plotted graphically and can be compared to other graphs of an ideal or wanted case in order to evaluate the condition of the pipe.
Introducing inspection tools with extended sensor capabilities however also mean introducing hardware that generates heat into the pipes, for example camera chips, processors, batteries and lighting means. Due to the pressure in the well and other factors, high temperatures may be present in the environment were the apparatus is inserted. These temperatures are usually up to 150 degrees Celsius, but can reach an excess of 300 degrees Celsius. The hardware within the device that generates heat is sensible to high temperatures. As a consequence, inserting the apparatus in the well pipe may heat up the apparatus both externally and internally to a critical temperature, giving a threshold for how long the device can be placed in the well pipe without causing damage to the hardware. This means that the hardware necessary for performing inspection of the well needs to be cooled to be able to extend the threshold value and thus the working time to be as long as possible and thereby enable a complete inspection to be performed.
However, not all the hardware installed in an inspection tool has the same sensitivity towards high temperatures. For example, power supply, camera optics and sensors are way more temperature tolerant than processors, chips and camera electronics, even if the last mentioned devices are the one producing the most heat during operation.
As more and more active components and electronics are introduced in inspection tools, the need for cooling is increasing. This is in prior art done by passive cooling, employing combinations of heat insulating and reflecting materials in combination with storage materials, separating into separate chambers and vacuum to extend this timeframe. However, this does not provide sufficient cooling for fully equipped inspection tools.
It is therefore a need for a new cooling assembly for inspection tools with heat generating components installed operating in high pressure environments.